Last November, as available via: Exxon Lubricating Oil from CoalTL Wax | Research & Development | News; we sent you report of:United States Patent: 5290426 - High Porosity ... Catalyst and its Use; 1994; Assignee: Exxon Research and Engineering; which, it's title aside, actually disclosed a process technology that could "produce high yields (of liquid hydrocarbons) from a synthetic Fischer-Tropsch wax".
Such "synthetic Fischer-Tropsch wax", we remind you, is a buildup of semi-solid hydrocarbons that can accumulate on the surfaces of catalysts used to condense synthesis gas, derived from, among other sources, Coal, into liquid hydrocarbons.
Herein, we see that Mobil Oil, as well, before the ExxonMobil merger, and prior to that Exxon patent, had developed their own technology to further process and refine the Fischer-Tropsch wax by-product of indirect Coal liquefaction.
Moreover, our tax money was used to pay for the research and development.
Comment follows excerpts from the enclosed link to:
"United States Patent 4,684,756 - Process for Upgrading Wax from Fischer-Tropsch Synthesis
Date: August, 1987
Inventor: W. Rodman Derr, et. al., NJ
Assignee: Mobil Oil Corporation, NY
Abstract: The waxy liquid phase of an oil suspension of Fischer-Tropsch catalyst containing dissolved wax is separated out and the wax is converted by hydrocracking, dewaxing or by catalytic cracking with a low activity catalyst to provide a highly olefinic product which may be further converted to premium quality gasoline and/or distillate fuel.
Government Interests: The Government of the United States of America has rights in this invention pursuant to Contract No. DE-AC22-83PC60019 awarded by the U.S. Department of Energy.
Claims: A process for converting synthesis gas to liquid hydrocarbons comprising the steps of: charging said synthesis gas to a Fischer-Tropsch synthesis conversion zone containing a catalyst providing CO reducing characteristiccs to produce a waxy hydrocarbon liquid; separating hydrocarbon wax from said waxy liquid; catalytically cracking said wax in a fluidized bed of acid crystalline zeolite at cracking temperature under process conditions requiring a supply of heat to effect cracking ... .
(And) thereby producing olefinic liquid hydrocarbon crackate in the gasoline and distillate boiling range along with olefinic light gas;
(Recovering) distillate range hydrocarbons from the liquid crackate;
(And) further converting the olefinic gasoline range hydrocarbon crackate and olefinic light gas under oligomerization conditions ... to upgrade at least a portion of said olefinic crackate and olefinic light gas to distillate range hydrocarbon product and producing by-product light fuel gas;
(And) wherein the synthesis gas reaction of step (a) is carried out with a low H2 /CO ratio syngas ... .
The method ... which comprises contacting said wax ... with a ... cracking catalyst ... to produce an olefinic light gas and gasoline distillate.
Description: This invention is concerned with a process wherein the "wax" resulting from the Fischer-Tropsch synthesis reaction is catalytically upgraded into high quality gasoline and distillate products.
Processes are well known for converting coal ... to a gaseous mixture consisting primarily of hydrogen and carbon monoxide and/or dioxide. It is also well known that these gases (synthesis gas) will undergo conversion to reduction products of carbon monoxide such as hydrocarbons, over a fairly wide variety of catalysts under certain conditions of temperature and pressure. The Fischer-Tropsch process, for example, produces a range of liquid hydrocarbons ... .
More recently, it has been discovered that the conversion of synthesis gas into valuable products can be greatly enhanced by employing a special type of crystalline zeolite, exemplified by ZSM-5 in admixture with a carbon monoxide reduction catalyst.
It has also been discovered that a highly aromatic or highly olefinic gasoline of enhanced octane number or a gasoline plus distillate mixture, can be obtained in greater yield from synthesis gas utilizing a selected synthesis gas composition of low H2 /CO ratio in a relatively special Fischer-Tropsch syngas conversion operation and in a sequentially arranged dual reactor conversion process. Such a process is described in U.S. Pat. No. 4,279,830 which is incorporated herein by reference.
In any process using a slurried catalyst to convert the syngas to higher molecular weight hydrocarbons, it has been noted that when low yields of light gases are produced, a large fraction of the hydrocarbon products is a heavy ... wax. This product wax has to be separated from the catalyst and further upgraded to valuable products.
In order to ... maximize liquid fuel production, the Fischer-Tropsch synthesis is carried out with a low H2/CO ratio syngas in a slurried liquid phase catalyst reactor system to produce substantial yields of reactor-wax and low yields of methane plus ethane. The reactor wax, which is a high molecular weight highly paraffinic product, is thereafter upgraded by specialized cracking, hydrocracking or dewaxing processes to obtain premium quality gasoline ... .
An important aspect of this invention is directed to converting relatively low H2 /CO ratio syngas (1/1 or less H2 /CO ratio) wherein it is essential that the CO reducing catalyst used include water-gas shift activity or be characterized so that steam formed in the Fischer-Tropsch operation will react with charged CO to form H2.
The low H2/CO ratio syngas ... is obtained by gasification of coals ... .
The syngas is converted in the ... Fischer-Tropsch reactor (and, the) contact time of the syngas is chosen to provide high conversion per pass, (up to) to 95%.
This value depends on (several factors which can contribute) to a more satisfactory operation of the system for producing desired liquid wax products in high yields.
The low temperature operation contemplated is particularly desirable for reducing the production of C1 and C2 hydrocarbons, for reducing carbon build-up on the catalyst and for improving selectivity of the operation for producing high yields of reactor-wax which are highly paraffinic and of high molecular weight.
In any process using a slurried catalyst to convert the syngas to higher molecular weight hydrocarbons, it has been noted that when low yields of light gases are produced, a large fraction of the hydrocarbon products is a heavy C15.+ wax. This product wax has to be separated from the catalyst and further upgraded to valuable products. U.S. Pat. No. 4,423,265 discloses a process wherein the liquid carrier in a Fischer-Tropsch synthesis slurry reactor system is periodically or continually separated. The catalyst is removed from the liquid carrier and the liquid carrier is subjected to isomerization and cracking and a portion of the cracked and isomerized product is then returned with the catalyst to the reactor zone while the remainder of the product is recovered as a desired hydrocarbon or gasoline fraction.
It should be understood ... that any wax resulting from the Fischer-Tropsch synthesis reaction may be used in accordance with the invention and that high quality gasoline and distillate products also can be produced from Fischer-Tropsch waxes ... ."
--------------
Concerning the above-referenced US Patent, following, for clarity, is a link to and excerpts from:
"United States Patent: 4423265 - Syngas Conversions to Liquid Hydrocarbon Products
Date: December, 1983
Inventors: Yung-Feng Chu, et. al., NJ
Assignee: Mobil Oil Corporation, NY
Abstract: The liquid carrier in a Fischer-Tropsch synthesis slurry reactor system is periodically or continually separated and subjected to cracking and isomerization in the presence of suitable catalysts. The treated carrier is returned to the reactor system and the accumulation of high viscosity paraffin in the reactor slurry is minimized.
Claims: A process for converting synthesis gas to liquid hydrocarbons having a boiling range within that of gasoline and distillate comprising the steps of:
(Charging) synthesis gas to a Fischer-Tropsch synthess conversion zone ... in direct contact with a suspending liquid medium;
(And) separating at least a fraction of said suspending liquid medium containing dissolved heavier hydrocarbons from said catalyst particles ... ."
----------------
In any case, these sequential Mobil Oil Corporation developments, paid for in part by our tax dollars, demonstrate and establish technology that confirms earlier of our reports, in that:
Even the by-products of some indirect Coal-to-Liquid conversion processes, i.e., "heavier hydrocarbons" - the "wax resulting from the Fischer-Tropsch synthesis reaction" as above, which reaction catalytically processes "syngas ... obtained by gasification of coals" - can be reclaimed, after the condensation of that Coal-derived synthesis gas into liquid hydrocarbons, and themselves be further converted into "high quality gasoline and" other "distillate products".